Hemodialysis is a procedure where blood is withdrawn from the body into a machine that uses a dialyzer to filter wastes, and subsequently returned to the body in the filtered state so as to restore the electrolyte balance within the body. Hemodialysis can be performed using a single needle system or a double needle system. In general, insertion of a second needle is more difficult than that of the first needle and thus, using a single needle system is generally considered to ease some problems. However, the use of current single needle systems has many undesirable risk factors such as a higher risk of back filtration, blood recirculation and underdialysis.